Process of clam evisceration

ABSTRACT

A method for effecting the separation of visceral material from shucked clams is disclosed. Clean clam meat in essentially viscera-free form is obtained by subjecting shucked uneviscerated clam pieces to agitation in a hot aqueous medium for a controlled period of time. As a result of this step, the visceral material is transferred to the liquid medium and remains as a fully liquid body which can be separated from the pieces of clam meat. The recovered clam pieces may then be washed to remove any residual liquid or small fragments which remain on the surfaces of the pieces.

United States Patent Finley et al.

[54] PROCESS OF CLAM EVISCERATION [72] Inventors: Ronald K. Finley,Towson; Donald J. Langlois, Pasadena, both of Md.; Robert H. Nicholson,Lewes, Del.

521 U.S.Cl ..l46/222 51 lnt.Cl ..B0ld43/00 5s FieldoiSearch..l7/53,45,48,5l,52,65;

[56] References Cited UNITED STATES PATENTS 1,011,378 12/1911 Shaffer..l7/65 [451 May 2,1972

Primary ExaminerLucie H. Laudenslager Att0rneyRoy1ance, Abrams, Berdoand Kaul [5 7] ABSTRACT A method for effecting the separation ofvisceral material from shucked clams is disclosed. Clean clam meat inessentially viscera-free form is obtained by subjecting shuckeduneviscerated clam pieces to agitation in a hot aqueous medium for acontrolled period of time. As a result of this step, the visceralmaterial is transferred to the liquid medium and remains as a fullyliquid body which can be separated from the pieces of clam meat. Therecovered clam pieces may then be washed to remove any residual liquidor small fragments which remain on the surfaces of the pieces.

7 Claims, No Drawings PROCESS or CLAM EVISCERATION This inventionrelates to the production of clean, edible clam meat and, moreparticularly, to a unique process for effecting the separation ofvisceral material from shucked clams.

As is well known in the art, the processing of clams involves the stepsof removal of the meat from the shell, referred to as shucking of theclams, followed by the removal of the belly contents from the shuckedclams. In recent years, prior-art workers have proposed a variety ofmechanical and other techniques for processing clams. This isparticularly true in the case of techniques for shucking or removing theshells from clams. Thus it has been proposed, for example, to employvarious mechanical means which subject the shells to crushing orabrading operations. It has also been proposed to employ such mechanicalmeans in combination with heat treatment of the clams, the latterserving to facilitate removal of the clam meat from the clam shell. Inmore recent years, it has also been proposed to employ enzymes, or acombination thereof, for loosening and/or removing the edible tissue ormeat from the shells, as well as to effect (or aid in) the separation ofthe belly contents or visceral material from the shucked unevisceratedclam meat.

Despite prior-art efiorts, processing of clams on a commercial basis isstill done by procedures depending on manual labor. In the case ofdebellying, operators manually tear the belly away and wash thedebellied clam. This is obviously an operation too tedious,time-consuming and costly to be acceptable under present economicconditions.

Stated generally, this invention provides a highly efficient andsimplified method for separating the visceral material, i.e., the bellyand contents, from whole clams. The invention is based on the discoverythat clean clam meat can be recovered in essentially viscera-free formby subdividing the shucked clams and subjecting the pieces to agitationin a hot aqueous medium for a controlled period of time, with the resultthat the visceral material, being exposed by subdivision of the clam, isdisrupted hydraulically and distributed through the aqueous medium bysolution and dispersion. As a result of the agitation step, the visceralmaterial is transferred to the liquid medium and, through the solutionand dispersion of the visceral material results in a thickening of theaqueous medium. The aqueous medium remains as a fully liquid body whichcan be readily separated from the pieces of clam meat, with the clampieces then being recoverable as clean, essentially viscera-free piecesby simply washing away such residual liquid and fragments as may remainon the surfaces of the pieces.

It is accordingly a general object of this invention to provide aprocess for producing clean, eviscerated clam meat from shucked clams,said process not subject to the disadvantages of prior techniques.

Another and more particular object is to provide a highly efficient andsimplified process for effecting separation of visceral material fromclam meat, which method eliminates the need for manual operations andthe disadvantages associated therewith. I

Still another object is to provide a process for converting normallyinedible clams into edible clams suitable for human consumption.

Still another object is to provide a unique process for producing clean,edible clam pieces in essentially viscerafree form from chopped, shuckedpieces of uneviscerated clam meat.

The manner in which the foregoing and other objects are achieved inaccordance with the present invention will be better understood in viewof the following detailed description wherein particularly advantageousmethod and composition embodiments have been disclosed for illustrativepurposes.

As briefly discussed above, the present invention is based on theunexpected discovery that clean clam meat, in essentially viscera-freeform can be obtained by subjecting pieces of shucked uneviscerated clammeat to agitation in a hot aqueous medium for a controlled period oftime. In its broadest aspects, the method of the invention comprisessubdividing, as by grinding, shucked uneviscerated clams into smallpieces, subjecting the clam pieces to agitation in an aqueous mediummaintained at a temperature in the range of from to 150 F., continuingthe agitation for a period of at least 5 minutes, separating the clampieces from the aqueous medium and thereafter washing the recoveredpieces to remove any residue of the liquid medium.

The method of the invention is applicable to clams generally and as usedherein, the term clam is intended to include the generic class of clamsreferred to in the art as Pelecypoda and the wide variety of speciesthereof. Examples of such species include surf clams (Spisulasolidissima), soft shell clams (Mya arenan'a), mahogany or black quahogs(Artica islandica) and regular quahog clams Venus mercenaria).

In practicing the method of the invention, the clams are first shucked,i.e., manually or mechanically removing the meat from the shell, inaccordance with techniques well known in the industry. If desired theclams may first be heat treated to partially open the shell andfacilitate separation of the meat from the shell.

After the clams have been shucked, the uneviscerated clam meat ischopped or cut into small pieces or slices. In general the size of thepieces is not critical. However, the chopping operation should be suchthat at least a part of each clam, including the belly portion orvisceral material, is subdivided into pieces smaller than the bellyportion. Stated differently the chopping operation should be such thatthe peritoneum of each clam is at least partially intersected so thatthe viscera or belly content is exposed in part. In this regard it hasbeen found that small pieces on the order of about one-quarter inch byone-quarter inch to about 1 inch by 1 inch are particularlyadvantageous. Slices on the order of about /4 inch by 2 inches in lengthmay also be used. It should be understood that reference to a particularsize is intended to refer to an average, i.e., a given amount of choppedpieces may contain over and undersized pieces. Any suitable means orapparatus may be employed to chop or cut the clam meat into pieces.

Considering now the method of the invention in more detail, the piecesof uneviscerated clam meat are dispersed in an aqueous medium andsubjected to agitation for a period of at least 5 minutes. Thetemperature of the aqueous medium should be maintained in the range ofabout 100 to 150 F., with preferred ranges being on the order of 1 10 toF. To a considerable extent the invention is based on the discovery thatin subjecting the shucked pieces to agitation, under the controlledconditions set forth herein, the visceral material is disrupted andtransferred to the liquid medium as a solution and dispersion. Asindicated above, the pieces of clam meat should be subjected toagitation for a period of at least about 5 minutes. It has been foundthat the agitation may be continued for a period of from 5 minutes tomore than 2 hours, with the maximum or upper limit on the retention timebeing dictated only by practical or economical reasons. Preferred timeperiods are on the order of from about 5 to 30 minutes. While agitationmust be maintained throughout this processing step, the particular modeor apparatus employed to maintain the agitation is not critical. Forexample, agitation may be effected by a conventional bladed stirrer orby injecting high pressure steam and/or air through the aqueous medium,etc.

The concentration or percent by weight solids, i.e., the chopped clampieces, of the aqueous dispersion or slurry may vary widely withparticularly advantageous results being obtained at concentrations inthe range of about 30-70 percent by weight of the total system. Slurriesless concentrated than 10 percent are not recommended for practicalreasons whereas concentrations greater than 80 percent are difficult toagitate. From the above it will be seen that the concentration of theslurry is largely dependent upon process economics, the equipmentemployed, etc.

In carrying out the agitation step, any suitable apparatus, providede.g., with means for maintaining the aqueous dispersion under agitationand for controlling the temperature of the dispersion, etc., may beemployed. The method of the invention may be carried out batchwise or ona continuous basis. In the case of the latter, the shucked pieces ofclam meat may be subjected to agitation e.g., in a tubular reactorprovided with suitable baffles to insure intimate mixing, etc.

After the clam pieces have been subjected to agitation in the mannerdescribed above, they are separated from the aqueous medium and arewashed under conditions to remove any residue of the visceral material.Preferably this step is conducted by passing the recovered clam piecesonto a vibrating perforated screen provided with spray or jet washersdirected on the meat as it passes along the screen. However, again theparticular equipment employed is not critical and any conventionalwashing equipment may be used. If desired the washing step may beconducted with water at ambient temperature so as to reduce thetemperature of the clam pieces. The washed clam pieces are recovered andfurther processed, as by canning, in the conventional manner.

The invention will be further illustrated by the following exampleswhich set forth particularly advantageous method embodiments. While theexamples serve to illustrate the invention they are not intendedto limitit thereto.

EXAMPLE 1 One-hundred pounds of shucked uneviscerated surf clams wasground to pieces of approximately one-quarter inch by one-quarter inchsize in a conventional grinding machine. Approximately 100 gallons ofwater was preheated in a 150 gallon stainless steel jacketed vessel to130 F., using 100 p.s.i.g. steam. The 100 pounds of ground clam meat,including the visceral material, was then immersed in the heated waterin the stainless steel vessel and suspended by agitation. Steam wasintroduced into the outer jacket of the stainless steel vessel tomaintain the temperature of the aqueous slurry at 130 F. plus or minus 2F. Agitation was maintained by a threebladed propeller stirrer. Thesuspension was then agitated for a period of about 8 minutes, afterwhich the entire contents of the vessel were drained by gravity from thevessel and delivered onto a vibrating screen, with the liquid phasepassing through the screen and the clam meat remaining thereon. Thescreen was equipped with 85 p.s.i.g. spray washers which were directedonto the meat as it passed along the screen. The essentiallyviscera-free clam meat delivered at the end of the screen was charged toa cylindrical washer to remove any remaining sand orgrit. The cleaneviscerated clam meat was then canned in the conventional mannerfollowed by thermal processing. Comparison was made of the cannedproduct of this example with that from clams that were debelliedmanually, by experts in the field. The comparison showed that theproduct of this example was superior to that obtained from manuallydebellied clams in that the latter product contained an observableproportion of visceral material while the product of this example wasessentially vsicera-free. Further, the clam meat of this example wasfully equal in all respects to that obtained from the manually debelliedclams EXAMPLE 2 The procedure of Example 1 was repeated except that thetemperature of the water was heated and maintained at 100 F. Comparisonof the canned product of this example with that from clamsthat weredebellied manually showed that the product of this example was superiorto that obtained from manually debellied clams in the manner describedin Example l. In a series of further tests (4) the temperature of thewater was heated and maintained at 110 F., 120 F 140 F and 150 F. Thetest results were identical with Example 1, i.e., the product of eachtest, as compared to manually debellied clams, was superior to themanually debellied clams-in the manner described in Example 1.

EXAMPLE 3 In this Example, the procedure of Example VI was repeatedexcept that the water was heated and maintained at 50 F. The resultswere negative to the extent that a significant portion of the visceralmaterial was not separated from the meat.

EXAMPLE 4 The procedure of Example 1 was repeated except that theaqueous medium was not agitated. The results were negative with littleor no separation of the visceral material from the clam meat beingeffected.

EXAMPLE 5 The procedure of Example 1 was repeated except that mahoganyclams (Artica islandica) were substituted for the surf clams ofExample 1. The test results were identical to Example I. In a furthertest, regular quahog clams (Venus mercenari) were treated following theprocedure of Example 1. The test results were identical with that ofExample 1.

EXAMPLE 6 In this test, pounds of shucked uneviscerated surf clams,ground to pieces of approximately one-quarter inch by one-quarter inch,were dispersed in 25 gallons of water in a SO-gallon stainless steelvessel. The slurry was then continuously pumped through a series ofthree 2 feet O.D. by 8 feet long tubular reactors provided with internalbaffles to insure adequate mixing. The temperature of the slurry in thereactors was maintained at F. by introducing 100 p.s.i.g. steam inexternal jackets surrounding the reactors. The slurry was dischargedcontinuously from the reactors onto a vibrating screen as described inExample 1. The clean eviscerated clam meat was canned and compared withclams that were debel lied manually. The product of this Example wassuperior to that obtained from manually debellied clams in the mannerdescribed in Example 1.

EXAMPLE 7 The general procedure of Example 1 was repeated except thatthe clams were ground to pieces of about one-half inch by one-half inchsize. The test results were identical to that of Example l. In a furthertest, the size of the pieces was increased to 1 inch by 1 inch withequally good results as per Example 1.

What is claimed is:

1. A method for producing clean, edible clam meat from shuckeduneviscerated clams comprising the steps of:

chopping shucked uneviscerated clams into pieces,

agitating said clam pieces in an aqueous medium,

said aqueous medium being maintained at a temperature in the range offrom about 100 F. to F.,

continuing said agitation for a period of time of at least about 5minutes,

separating said clam pieces from said aqueous medium,

washing the recovered clam pieces under conditions to remove anyremaining visceral material, and

recovering the washed clam pieces in essentially viscerafree form.

2. A method in accordance with claim 1 wherein said aqueous medium ismaintained at a temperature in the range of about ll0l30F. and furthercomprising maintaining said agitation for a period of time from about 5minutes to 30 minutes.

3. A method in accordance with claim wherein said shucked unevisceratedclams are subjected to a chopping operation such that at least a part ofeach clam including the belly portion is subdivided into piecessignificantly smaller than the belly portion.

4. A method in accordance with claim 1 wherein said clam meat isselected from the group consisting of surf and mahogany clam meat.

5. A method for producing clean, edible clam meat from shuckeduneviscerated clams comprising the steps of:

chopping shucked uneviscerated clams into pieces such that remove anyremaining visceral material,

at least that part of each clam including the belly portion said washingstep being conducted with a liquid medium is subdivided into piecessignificantly smaller than the at a temperature in the range of about25-40 C., and belly portion, recovering the washed clam pieces inessentially visceraagitating said clam pieces in an aqueous medium, 5free form.

said aqueous medium bein maintained at a temperature 6. A method inaccordance with claim 5 wherein said washi h range f f about 110 140 F di a ing step is carried out by subjecting said recovered clam piecesvolume adequate to allow tumbling of said pieces, to j Ofwatef f pessure. continuing said agitation for a period of time from about 5 Amethod accordance with Claim 5 r in aid minutes to 30 minutes, 10chopped clam pieces in said aqueous medium are present in separatingsaid clam pieces from said aqueous medium, an amount of from 10-70 P yWeight of the washing the recovered clam pieces under conditions tosystemremove the residue of the aqueous medium and to UNITED STATESPATENT OFFICE CERTIFICATE OF CORRECTION Patent Dated May 2 1972 8)Ronald K. Finley 0t :11

' lnvvn to r It is certified that error appears in the above-identifiedpatent and that said Letters Patent are hereby corrected as shown below:

Herschel F. Porter, Lewes Delaware should be added as an inventor.

Signed and sealed this 2nd day of January 1973.

(SEAL) Attest:

EDWARD M. FLETCHER,JR. ROBERT GOTTSCHALK Attosting Officer Commissionerof Patents FORM PO-IOSO (10-69) USCOMM-DC 60376-1 69 at us. GOVERNMENTPRINTING OFFICE: 1969 0-366-334,

1. A method for producing clean, edible clam meat from shuckeduneviscerated clams comprising the steps of: chopping shuckeduneviscerated clams into pieces, agitating said clam pieces in anaqueous medium, said aqueous medium being maintained at a temperature inthe range of from about 100* F. to 150* F., continuing said agitationfor a period of time of at least about 5 minutes, separating said clampieces from said aqueous medium, washing the recovered clam pieces underconditions to remove any remaining visceral material, and recovering thewashed clam pieces in essentially viscera-free form.
 2. A method inaccordance with claim 1 wherein said aqueous medium is maintained at atemperature in the range of about 110*-130*F. and further comprisingmaintaining said agitation for a period of time from about 5 minutes to30 minutes.
 3. A method in accordance with claim - wherein said shuckeduneviscerated clams are subjected to a chopping operation such that atleast a part of each clam including the belly portion is subdivided intopieces significantly smaller than the belly portion.
 4. A method inaccordance with claim 1 wherein said clam meat is selected from thegroup consisting of surf and mahogany clam meat.
 5. A method forproducing clean, edible clam meat from shucked uneviscerated clamscomprising the steps of: chopping shucked uneviscerated clams intopieces such that at least that part of each clam including the bellyportion is subdivided into pieces significantly smaller than the bellyportion, agitating said clam pieces in an aqueous medium, said aqueousmedium being maintained at a temperature in the range of from about110*-140* F. and in a volume adequate to allow tumbling of said pieces,continuing said agitation for a period of time from about 5 minutes to30 minutes, separating said clam pieces from said aqueous medium,washing the recovered clam pieces under conditions to remove the residueof the aqueous medium and to remove any remaining visceral material,said washing step being conducted with a liquid medium at a temperaturein the range of about 25*-40* C., and recovering the washed clam piecesin essentially viscera-free form.
 6. A method in accordance with claim 5wherein said washing step is carried out by subjecting said recoveredclam pieces to jets of water under pressure.
 7. A method in accordancewith claim 5 wherein said chopped clam pieces in said aqueous medium arepresent in an amount of from 10-70 percent by weight of the totalsystem.